The present invention relates to a liquid pump and, more particularly, to a clean-in-place pump of the type utilized in sanitary food processing equipment.
Many sanitary food processes require that the equipment being used be cleaned-in-place. That is, a cleaning solution is circulated through the equipment to clean it rather than disassembling the equipment. Electrically driven centrifugal pumps are often used in such equipment. In such a pump there is formed a pocket in the wall of the pump housing, generally where shaft seal is mounted adjacent to the impeller hub, where particles in the fluid being pumped may become entrapped. When a cleaning solution is circulated through such a pump, the particles may not necessarily be flushed out with the result that subsequent food batches introduced into the pump may become contaminated thereby.
United States Patent No. 3,481,273 to Werra dislcoses a sanitary processing centrifugal pump of the above type in which angularly disposed, circumferentially spaced grooves are formed on the drive shaft for the impeller, and on the interior of the hub of the impeller. The grooves cause turbulence which is suposed to flush the hub pocket and adjacent parts as the impeller hub and shaft rotate. It will be appreciated, however, that the forming of angular grooves on the drive shaft for the impeller, and in the interior of the impeller hub is a costly operation.
It is therefore the object of the present invention to provide a clean-in-place pump suitable for use in sanitary food processing equipment in which the hub pocket region may be efficiently flushed out without the requirement of utilizing the angular slots incorporated in the Werra pump.